Why were there twelve labours of Heracles, not ten?

The Labours of Heracles

The oracle at Delphi tells Heracles to serve Eurystheus at Tiryns for twelve years and complete ten labours. Eurystheus later refuses to count two of the ten, so two more are added and the total reaches twelve. Apollodorus lists the twelve in one order, and the Temple of Zeus at Olympia carves them in another. The two do not even agree on whether the last labour, the fetching of Cerberus, belongs in the series at all.

In short

At Delphi, the Pythia calls Alcides “Hercules” for the first time and sends him to serve Eurystheus at Tiryns for twelve years, performing ten labours, not twelve (Apollodorus, Library 2.4.12).
Eurystheus refuses to count the Lernaean hydra, because Iolaus helps land the blow, and the Augean stables, because Heracles had agreed a price with Augeas for the work (Apollodorus, Library 2.5.2, 2.5.5).
The count reaches twelve because of the two refusals: “Eurystheus ordered Hercules, as an eleventh labour, to fetch golden apples from the Hesperides, for he did not acknowledge the labour of the cattle of Augeas nor that of the hydra” (Library 2.5.11).
The Temple of Zeus at Olympia, built 470 to 456 BC, carries all twelve labours on its metopes, six over the front porch and six over the back porch. It is the earliest surviving set to fix the labours in stone.
The description of those metopes by Pausanias ends on the cleaning of the Augean stables and never names Cerberus at all (Description of Greece 5.10.9).
Pausanias records two traditions about the first games at Olympia that do not agree. In one, an earlier Heracles, one of the Cretan Dactyls, held and named them. In the other, generations later, Heracles son of Amphitryon, the Heracles of the labours, held them again after conquering Elis (5.7.6, 5.7.9, 5.8.3).

Ten labours, set at Delphi

The goddess Hera drives Heracles mad, and in his madness he kills his own children. Afterwards he is purified of the killing and lives in exile. He goes to Delphi to ask the oracle there, a shrine where people put their questions to the gods, where he should live.

The Pythia, who speaks for the oracle, calls him Hercules for the first time, in place of his earlier name, Alcides. She tells him to settle at Tiryns and serve Eurystheus for twelve years. He must perform ten labours, or tasks, that Eurystheus will set him. When the tasks are done, she says, he will become immortal (Apollodorus, Library 2.4.12).

The ancient writer Apollodorus gives the labours in this order: the Nemean lion, the Hydra, the hind, the boar, the stables, the birds, the bull, the mares, the belt and the cattle. Then come the apples of the Hesperides and, last, Cerberus. The oracle asked for ten. The list reaches twelve only because Eurystheus rejects two of the tasks along the way.

Two refused, two added

The first rejected labour is the Lernaean hydra. Eurystheus refuses it because Heracles does not defeat it alone. His nephew Iolaus helps him stop the severed heads from growing back. So Eurystheus rules that Iolaus’s part makes the labour invalid (Library 2.5.2).

The second is the Augean stables, and the reason is different. Before he starts the work, Heracles makes a bargain with King Augeas: a tenth of the herd if he clears the dung in a single day. He does not tell Augeas that Eurystheus has ordered the task. Eurystheus voids this labour too, “alleging that it had been performed for hire”. In his view it was a job done for pay, and not a labour performed as commanded (Library 2.5.5).

With two of the ten refused, eight stand. After eight years and a month, Eurystheus orders the apples of the Hesperides as an eleventh labour, because he has refused both the stables and the Hydra (Library 2.5.11). Cerberus becomes the twelfth.

These last two tasks replace the two that Eurystheus struck from the original ten. That is why the labours number twelve, although the oracle set ten.

A different order at Olympia

Apollodorus put together his Library long after the labours already had a temple to show them. The Temple of Zeus at Olympia, built 470 to 456 BC, carries all twelve as carvings on its metopes, the carved panels set high along the outside of the temple. Modern scholars think this set did much to fix the number of labours at twelve.

The ancient traveller Pausanias, writing long after the temple was built, saw the metopes in place and described them. One side showed the boar, Diomedes, the cattle of Geryon, Atlas and the stables. The other showed the belt of the Amazon, the deer, the bull, the birds, the Hydra and the lion. His sentence names eleven labours. Cerberus is missing.

Where the labours end

Long before Apollodorus wrote his list, the playwright Euripides had already chosen where the series ends. In his play Heracles, the chorus of singers goes through the lion, the deer, the apples, the belt, the hydra and the cattle of Geryon. Then it turns to the last labour. Heracles “has now sailed” to the house of Hades, “the goal of his labors” (Heracles 425 to 427).

So for Euripides, as for Apollodorus, the trip down to fetch Cerberus, the Hound of Hades, is where the count ends. At Olympia, as Pausanias describes it, that is the very labour left out.

Pausanias records another disagreement about Olympia. Local historians of Elis credit the earliest games to a different Heracles. He was one of five Cretan Dactyls who guarded the infant Zeus. Later in the same book, Heracles son of Amphitryon holds the games after conquering Elis. Pausanias keeps both founders in his text.

What stands on the ground

The Temple of Zeus was excavated in 1875 and 1876, and the metopes came out of the ground in pieces. Most are now in the Archaeological Museum of Olympia, and some pieces are in the Louvre.

On the Argolid plain stands Tiryns, the citadel the oracle names. This is where the Pythia sends Heracles to serve Eurystheus. In Apollodorus, a frightened Eurystheus first refuses to let Heracles through the gates here. He has him show the proof of each labour outside the walls instead (Library 2.4.12, 2.5.1).

Excavation at Tiryns began in 1876 and has continued on and off since. The Cyclopean walls, which gave this style of stonework its name, still stand over the citadel.

Places to visit

Nafplio

Peloponnese

In Apollodorus, the Pythia sends Heracles to Tiryns to serve Eurystheus for twelve years. There, after the first labour, a frightened Eurystheus shuts him out of the city and has him show the proof of each labour at the gates, and the first two labours on every list, the Nemean lion and the Lernaean hydra, both belong to the same stretch of the Argolid plain around the citadel.
Nafplio
Olympia

Peloponnese

The Temple of Zeus at Olympia carries all twelve labours on its metopes, six above the front porch and six above the back porch, but the description of them by Pausanias ends on the cleaning of the Augean stables and never mentions Cerberus. Pausanias also records two traditions about the first games at Olympia that do not agree, one crediting an earlier Cretan Dactyl also named Heracles, the other crediting Heracles son of Amphitryon, who held them again after conquering Elis.
Olympia